The present invention relates to a photographic printer and more particularly to an apparatus for straightening the curl of a developed photographic film contained within a cassette in the form of roll before printing the film.
Recently, there have been proposals to record photographing information, print instruction information, user identification information, or the like on a recording medium such as a transparent magnetic recording layer formed in a photographic film, e.g., negative film, a magnetic recording sheet attached to a cassette containing an unexposed negative film, and a memory IC built in a cassette (see Japanese Patent Laid-open Publications Nos. 62-103625, 62-208028, 1-279231, and 1-289948). Various information recorded on such a recording medium is read by a photographic printer or the like to use it for exposure control or the like.
Conventionally, in a laboratory a negative film roll is cut into a plurality of negative film pieces having four to six frames each. Each negative film piece is contained within the pocket of a film sheath for return to a user. If the above-mentioned typed information had been recorded on a cassette in some manner, it would be necessary for a user to take custody of an empty cassette as well as the film sheaths containing the negative film pieces. If the cassette were lost, information recorded on the cassette could not be used to perform extra printing, for example, to make additional photoprints, or for other purposes. If such information was recorded on a transparent magnetic recording layer of a negative film, such a problem will not arise, but the information that could be recorded that way would be restricted. For example, although it is convenient if information common to all frames is recorded on the film leader, such common information preferably should be recorded on the transparent magnetic recording layer of each frame, taking into consideration that the negative film may be cut into negative film pieces
The above problem can be solved by winding a developed negative film within a cassette without cutting it into negative film pieces. Using an empty cassette as a container of a developed negative film is disclosed in Japanese Patent Laid-open Publications Nos. 1-279250 and 2-9519.
In order to reduce the amount of space necessary to contain a developed negative film, it is effective to wind the negative film on a small diameter spool. An ordinary negative film using triacetyl cellulose (TAC) as a base has a strong tendency to curl when wound in a coil. If a negative film having a curl is printed, there is a fear of lowering the print quality. Currently, there exists a well known practice of placing a negative film between two glass plates to remove any curl the film may have. This method, however, is associated with problems in which Newton's rings are likely to be produced, dust is likely to attach, frame adjustment is difficult, and the like.